Phosphoinositide 3-kinase inhibitors

ABSTRACT

A compound of formula I: or a pharmaceutically acceptable salt thereof, wherein: R 1 , R 2 , R 3 , R and R 6  are each independently (LQ) m Y; R 4  is H, halogen, optionally substituted aryl or optionally substituted alkyl; and; each X is independently CR 7  or N. The compounds are PI3K inhibitors and therefore have potential utility in therapy.

FIELD OF THE INVENTION

The present invention relates to novel compounds which act as inhibitors of the class IA phosphoinositide 3-kinase enzyme, PI3K-p110δ, for the treatment of cancer, immune and inflammatory diseases.

BACKGROUND OF THE INVENTION

The phosphoinositide 3-kinases (PI3Ks) constitute a family of lipid kinases involved in the regulation of a network of signal transduction pathways that control a range of cellular processes. PI3Ks are classified into three distinct subfamilies, named class I, II, and III based upon their substrate specificities. Class IA PI3Ks possess a p110α, p110β, or p110δ catalytic subunit complexed with one of three regulatory subunits, p85α, p85β or p55δ. Class IA PI3Ks are activated by receptor tyrosine kinases, antigen receptors, G-protein coupled receptors (GPCRs), and cytokine receptors. The class IA PI3Ks primarily generate phosphatidylinositol-3,4,5-triphosphate (PI(3,4,5)P₃), a second messenger that activates the downstream target AKT. The consequences of biological activation of AKT include tumour cell progression, proliferation, survival and growth, and there is significant evidence suggesting that the PI3K/AKT pathway is dysregulated in many human cancers. Additionally, PI3K activity has been implicated in endocrinology, cardiovascular disease, immune disorders and inflammation. It has been established that PI3K-p110δ plays a critical role in the recruitment and activation of immune and inflammatory cells. PI3K-p110δ is also upregulated in a number of human tumours and plays a key role in tumour cell proliferation and survival.

Compounds which are able to modulate p110δ activity have important therapeutic potential in cancer and immune and inflammatory disorders.

SUMMARY OF THE INVENTION

The present invention is a compound of formula I:

or a pharmaceutically acceptable salt thereof, wherein:

R₁, R₂, R₃, R₅ and R₆ are each independently (LQ)_(m)Y;

each L is independently a direct bond, C₁-C₁₀ alkylene, C₂-C₁₀ alkenylene, C₂-C₁₀ alkynylene, arylene or C₃-C₁₀ cycloalkylene;

each Q is independently a direct bond, heteroarylene, a heterocycle linker, —O—, —NR₇—, —OC(O)—, —C(O)NR₇—, —SO₂—, —SO₂—NR₇—, —NR₇—C(O)—NR₇—, —N—SO₂—NR₇—, —C(halogen)_(a)(R_(7(2-a)))—, —NR₈R₉—, —C(O)NR₈R₉—, where R₈ and R₉ together with the nitrogen to which they are attached form a 5 to 7-membered heterocycle linker;

each R₇ is independently H or C₁-C₆ alkyl;

m is from 0 to 5;

Y is H, C₁-C₁₀ alkyl, C₂-C₁₀ alkenyl, C₂-C₁₀ alkynyl, aryl, C₃-C₁₀ cycloalkyl, heterocycle, heteroaryl, —OR₇, —N(R₇)₂, —C(O)R₇, —C(O)OR₇, —C(O)N(R₇)₂, —N(R₇)₂, —SO₂—R₇, —SO₂—N(R₇)₂, —N—C(O)—N(R₇)₂, —N—SO₂—N(R₇)₂, halogen, —C(halogen)_(b)R_(7(3-b)), —CN, —NR₈R₉—, —C(O)NR₈R₉, where R₈ and R₉ together with the nitrogen to which they are attached form a 5- to 7-membered heterocycle;

b is from 1 to 3;

a is 1 or 2;

R₄ is H, halogen, optionally substituted aryl or optionally substituted alkyl; and;

each X is independently CR₇ or N,

wherein each aryl, heteroaryl or heterocycle is optionally substituted with up to three substituents selected from C₁-C₈ alkyl, hydroxy, C₁-C₃ hydroxyalkyl, C₁-C₃ alkoxy, C₁-C₃ haloalkoxy, amino, C₁-C₃ mono alkylamino, C₁-C₃ bis alkylamino, C₁-C₃ acylamino, C₁-C₃ aminoalkyl, mono (C₁-C₃ alkyl) amino C₁-C₃ alkyl, bis (C₁-C₃ alkyl) amino C₁-C₃ alkyl, C₁-C₃-acylamino, C₁-C₃ alkyl sulfonylamino, halo, nitro, cyano, trifluoromethyl, carboxy, C₁-C₃ alkoxycarbonyl, aminocarbonyl, mono C₁-C₃ alkyl aminocarbonyl, bis C₁-C₃ alkyl aminocarbonyl, —SO₃H, C₁-C₃ alkylsulfonyl, aminosulfonyl, mono C₁-C₃ alkyl aminosulfonyl and bis C₁-C₃-alkyl aminosulfonyl.

DESCRIPTION OF PREFERRED EMBODIMENTS

For the avoidance of doubt, the term “R₁, R₂, R₃, R₅ and R₆ are each independently (LQ)_(m)Y” means:

When m is 0, R_(n) is Y,

When m is 1, R_(n) is L-Q-Y;

When m is 2, R_(n) is L-Q-L-Q-Y (and each L and each Q group are the same or different);

When m is 3, R_(n) is L-Q-L-Q-L-Q-Y (and each L and each Q group are the same or different); etc

Preferably m is 0 or 1.

As used herein, “alkyl” means a C₁-C₁₀ alkyl group, which can be linear or branched. Preferably, it is a C₁-C₆ alkyl moiety. More preferably, it is a C₁-C₄ alkyl moiety. Examples include methyl, ethyl, n-propyl and t-butyl. It may be divalent, e.g. propylene. In general, the suffix “-ene” means that the group is divalent.

As used herein, “cycloalkyl” contains from 3 to 10 carbon atoms. It may be monovalent or divalent.

As used herein, “alkenyl” means a C₂-C₁₀ alkenyl group. Preferably, it is a C₂-C₆ alkenyl group. More preferably, it is a C₂-C₄ alkenyl group. The alkenyl radicals may be mono- or di-saturated, more preferably monosaturated. Examples include vinyl, allyl, 1-propenyl, isopropenyl and 1-butenyl. It may be divalent, e.g. propenylene

As used herein, “alkynyl” is a C₂-C₁₀ alkynyl group which can be linear or branched. Preferably, it is a C₂-C₄ alkynyl group or moiety. It may be divalent.

Each of the C₁-C₁₀ alkyl, C₂-C₁₀ alkenyl and C₂-C₁₀ alkynyl groups may be optionally substituted with each other, i.e. C₁-C₁₀ alkyl optionally substituted with C₂-C₁₀ alkenyl. They may also be optionally substituted with aryl, cycloalkyl (preferably C₃-C₁₀), aryl or heteroaryl. They may also be substituted with any of the “optional substituents” defined below.

As used herein, “aryl” means a monocyclic, bicyclic, or tricyclic monovalent or divalent aromatic radical, such as phenyl, biphenyl, naphthyl, anthracenyl, which can be optionally substituted with up to five substituents preferably selected from the group of C₁-C₆ alkyl, hydroxy, C₁-C₃ hydroxyalkyl, C₁-C₃ alkoxy, C₁-C₃ haloalkoxy, amino, C₁-C₃ mono alkylamino, C₁-C₃ bis alkylamino, C₁-C₃ acylamino, C₁-C₃ aminoalkyl, mono (C₁-C₃ alkyl) amino C₁-C₃ alkyl, bis(C₁-C₃ alkyl) amino C₁-C₃ alkyl, C₁-C₃-acylamino, C₁-C₃ alkyl sulfonylamino, halo, nitro, cyano, trifluoromethyl, carboxy, C₁-C₃ alkoxycarbonyl, aminocarbonyl, mono C₁-C₃ alkyl aminocarbonyl, bis C₁-C₃ alkyl aminocarbonyl, —SO₃H, C₁-C₃ alkylsulfonyl, aminosulfonyl, mono C₁-C₃ alkyl aminosulfonyl and bis C₁-C₃-alkyl aminosulfonyl.

As used herein, “heteroaryl” means a monocyclic, bicyclic or tricyclic monovalent aromatic radical containing up to four heteroatoms selected from oxygen, nitrogen and sulfur, such as thiazolyl, tetrazolyl, imidazolyl, oxazolyl, isoxazolyl, thienyl, pyrazolyl, pyridinyl, pyrazinyl, pyrimidinyl, indolyl, quinolyl, isoquinolyl, said radical being optionally substituted with up to three substituents preferably selected from the group of C₁-C₆ alkyl, hydroxy, C₁-C₃ hydroxyalkyl, C₁-C₃ alkoxy, C₁-C₃ haloalkoxy, amino, C₁-C₃ mono alkylamino, C₁-C₃ bis alkylamino, C₁-C₃ acylamino, C₁-C₃ aminoalkyl, mono (C₁-C₃ alkyl) amino C₁-C₃ alkyl, bis (C₁-C₃ alkyl) amino C₁-C₃ alkyl, C₁-C₃-acylamino, C₁-C₃ alkyl sulfonylamino, halo, nitro, cyano, trifluoromethyl, carboxy, C₁-C₃ alkoxycarbonyl, aminocarbonyl, mono C₁-C₃ alkyl aminocarbonyl, bis C₁-C₃ alkyl aminocarbonyl, —SO₃H, C₁-C₃ alkylsulfonyl, aminosulfonyl, mono C₁-C₃ alkyl aminosulfonyl and bis C₁-C₃-alkyl aminosulfonyl.

As used herein, “heterocycle” is a mono- or di-valent non-aromatic carbocyclic radical containing up to 4 heteroatoms selected from oxygen, nitrogen and sulfur. The word ‘linker’ has been used herein to mean di-valent. If the heterocycle is a di-valent linker, the heterocycle may be attached to neighbouring groups through a carbon atom, or through one of the heteroatoms, e.g. a N.

The above groups can be followed by the suffix -ene. This means that the group is divalent, i.e. a linker group.

As used herein, “optionally substituted” preferably means optionally substituted with up to three “optional substituents” selected from C₁-C₈ alkyl, hydroxy, C₁-C₃ hydroxyalkyl, C₁-C₃ alkoxy, C₁-C₃ haloalkoxy, amino, C₁-C₃ mono alkylamino, C₁-C₃ bis alkylamino, C₁-C₃ acylamino, C₁-C₃ aminoalkyl, mono (C₁-C₃ alkyl) amino C₁-C₃ alkyl, bis (C₁-C₃ alkyl) amino C₁-C₃ alkyl, C₁-C₃-acylamino, C₁-C₃ alkyl sulfonylamino, halo e.g. F, Cl, nitro, cyano, trifluoromethyl, carboxy, C₁-C₃ alkoxycarbonyl, aminocarbonyl, mono C₁-C₃ alkyl aminocarbonyl, bis C₁-C₃ alkyl aminocarbonyl, —SO₃H, C₁-C₃ alkylsulfonyl, aminosulfonyl, mono C₁-C₃ alkyl aminosulfonyl and bis C₁-C₃-alkyl aminosulfonyl.

In R₄, preferably halogen is fluorine.

Preferably, R₁ is an optionally substituted aryl or optionally substituted heterocycle, preferably a nitrogen-containing one. More preferably, R₁ is morpholinyl, piperidinyl, piperazinyl, pyrrolidinyl, cyclohexylamino, cyclopentylamino, piperidin-4-yl, N-acetylpiperazinyl, thiomorpholinyl, thiomorpholinyldioxide, 4-hydroxyethylpiperidinyl, and 4-hydroxypiperidinyl. Still more preferably, R₁ is represented by any of the following structures:

Most preferably, R₁ is morpholino.

Preferably, R₂ is C₁-C₆ alkyl, H, halogen or C(halogen)_(b)R_(7(3-b)), where b is from 1 to 3. More preferably R₂ is C₁-C₆ alkyl or H. More preferably R₂ is H.

In a preferred embodiment at least one X is CH. Preferably, each X is CH.

Preferably, R₂ is H.

Preferably, R₄ is H.

Preferably, R₅ and/or R₆ is H. More preferably, R₅ and R₆ are H.

Preferably, R₃ is NR₇R₇.

Preferably, R₃ is NR₇C(O)(C₁-C₁₀ alkylene)NR₈R₉.

Preferably, R₃ is NR₇C(O)(C₁-C₁₀ alkylene)NR₇R₇.

In a preferred embodiment, a compound of the invention is as exemplified herein, i.e. compound A, B or C.

For the avoidance of doubt, a moiety designated as, for example, —C(O)NR₇—, is not direction specific, it can also be positioned as —NR₇—C(O)—.

A pharmaceutical composition of the invention typically contains up to 85 wt % of a compound of the invention. More typically, it contains up to 50 wt % of a compound of the invention. Preferred pharmaceutical compositions are sterile and pyrogen-free. Further, the pharmaceutical compositions provided by the invention typically contain a compound of the invention which is a substantially pure optical isomer. Preferably, the pharmaceutical composition comprises a pharmaceutically acceptable salt form of a compound of the invention.

As used herein, a pharmaceutically acceptable salt is a salt with a pharmaceutically acceptable acid or base. Pharmaceutically acceptable acids include both inorganic acids such as hydrochloric, sulfuric, phosphoric, diphosphoric, hydrobromic or nitric acid and organic acids such as citric, fumaric, maleic, malic, ascorbic, succinic, tartaric, benzoic, acetic, methanesulfonic, ethanesulfonic, salicylic, stearic, benzenesulfonic or p-toluenesulfonic acid. Pharmaceutically acceptable bases include alkali metal (e.g. sodium or potassium) and alkali earth metal (e.g. calcium or magnesium) hydroxides and organic bases such as alkyl amines, aryl amines or heterocyclic amines.

For the avoidance of doubt, the present invention also embraces prodrugs which react in vivo to give a compound of the present invention.

The compounds of the invention may be prepared by synthetic routes that will be apparent to those skilled in the art, e.g. based on the Examples.

The compounds of the invention and compositions comprising them may be administered in a variety of dosage forms. In one embodiment, a pharmaceutical composition comprising a compound of the invention may be formulated in a format suitable for oral, rectal, parenteral, intranasal or transdermal administration or administration by inhalation or by suppository. Typical routes of administration are parenteral, intranasal or transdermal administration or administration by inhalation.

The compounds of the invention can be administered orally, for example as tablets, troches, lozenges, aqueous or oily suspensions, dispersible powders or granules. Preferred pharmaceutical compositions of the invention are compositions suitable for oral administration, for example tablets and capsules.

The compounds of the invention may also be administered parenterally, whether subcutaneously, intravenously, intramuscularly, intrasternally, transdermally or by infusion techniques. The compounds may also be administered as suppositories.

The compounds of the invention may also be administered by inhalation. An advantage of inhaled medications is their direct delivery to the area of rich blood supply in comparison to many medications taken by oral route. Thus, the absorption is very rapid as the alveoli have an enormous surface area and rich blood supply and first pass metabolism is bypassed. A further advantage may be to treat diseases of the pulmonary system, such that delivering drugs by inhalation delivers them to the proximity of the cells which are required to be treated.

The present invention also provides an inhalation device containing such a pharmaceutical composition. Typically said device is a metered dose inhaler (MDI), which contains a pharmaceutically acceptable chemical propellant to push the medication out of the inhaler.

The compounds of the invention may also be administered by intranasal administration. The nasal cavity's highly permeable tissue is very receptive to medication and absorbs it quickly and efficiently, more so than drugs in tablet form. Nasal drug delivery is less painful and invasive than injections, generating less anxiety among patients. By this method absorption is very rapid and first pass metabolism is usually bypassed, thus reducing inter-patient variability. Further, the present invention also provides an intranasal device containing such a pharmaceutical composition.

The compounds of the invention may also be administered by transdermal administration. The present invention therefore also provides a transdermal patch containing a compound of the invention.

The compounds of the invention may also be administered by sublingual administration. The present invention therefore also provides a sub-lingual tablet comprising a compound of the invention.

A compound of the invention may also be formulated with an agent which reduces degradation of the substance by processes other than the normal metabolism of the patient, such as anti-bacterial agents, or inhibitors of protease enzymes which might be the present in the patient or in commensural or parasite organisms living on or within the patient, and which are capable of degrading the compound.

Liquid dispersions for oral administration may be syrups, emulsions and suspensions.

Suspensions and emulsions may contain as carrier, for example a natural gum, agar, sodium alginate, pectin, methylcellulose, carboxymethylcellulose, or polyvinyl alcohol. The suspension or solutions for intramuscular injections may contain, together with the active compound, a pharmaceutically acceptable carrier, e.g. sterile water, olive oil, ethyl oleate, glycols, e.g. propylene glycol, and if desired, a suitable amount of lidocaine hydrochloride.

Solutions for injection or infusion may contain as carrier, for example, sterile water or preferably they may be in the form of sterile, aqueous, isotonic saline solutions.

The compounds of the present invention can be used in both the treatment and prevention of cancer and can be used in a monotherapy or in a combination therapy. When used in a combination therapy, the compounds of the present invention are typically used together with small chemical compounds such as platinum complexes, anti-metabolites, DNA topoisomerase inhibitors, radiation, antibody-based therapies (for example herceptin and rituximab), anti-cancer vaccination, gene therapy, cellular therapies, hormone therapies or cytokine therapy.

In one embodiment of the invention a compound of the invention is used in combination with another chemotherapeutic or antineoplastic agent in the treatment of a cancer. Examples of such other chemotherapeutic or antineoplastic agents include platinum complexes including cisplatin and carboplatin, mitoxantrone, vinca alkaloids for example vincristine and vinblastine, anthracycline antibiotics for example daunorubicin and doxorubicin, alkylating agents for example chlorambucil and melphalan, taxanes for example paclitaxel, antifolates for example methotrexate and tomudex, epipodophyllotoxins for example etoposide, camptothecins for example irinotecan and its active metabolite SN38 and DNA methylation inhibitors for example the DNA methylation inhibitors disclosed in WO02/085400.

According to the invention, therefore, products are provided which contain a compound of the invention and another chemotherapeutic or antineoplastic agent as a combined preparation for simultaneous, separate or sequential use in alleviating a cancer. Also provided according to the invention is the use of compound of the invention in the manufacture of a medicament for use in the alleviation of cancer by co-administration with another chemotherapeutic or antineoplastic agent. The compound of the invention and the said other agent may be administrated in any order. In both these cases the compound of the invention and the other agent may be administered together or, if separately, in any order as determined by a physician.

The PI3K inhibitors of the present invention may also be used to treat abnormal cell proliferation due to insults to body tissue during surgery. These insults may arise as a result of a variety of surgical procedures such as joint surgery, bowel surgery, and cheloid scarring. Diseases that produce fibrotic tissue that may be treated using the PI3K inhibitors of the present invention include emphysema. Repetitive motion disorders that may be treated using the present invention include carpal tunnel syndrome. An example of a cell proliferative disorder that may be treated using the invention is a bone tumour.

Proliferative responses associated with organ transplantation that may be treated using PI3K inhibitors of the invention include proliferative responses contributing to potential organ rejections or associated complications. Specifically, these proliferative responses may occur during transplantation of the heart, lung, liver, kidney, and other body organs or organ systems.

Abnormal angiogenesis that may be treated using this invention include those abnormal angiogenesis accompanying rheumatoid arthritis, ischemic-reperfusion related brain edema and injury, cortical ischemia, ovarian hyperplasia and hypervascularity, polycystic ovary syndrome, endometriosis, psoriasis, diabetic retinopathy, and other ocular angiogenic diseases such as retinopathy of prematurity (retrolental fibroplastic), macular degeneration, corneal graft rejection, neuroscular glaucoma and Oster Webber syndrome.

Examples of diseases associated with uncontrolled angiogenesis that may be treated according to the present invention include, but are not limited to retinal/choroidal neovascularisation and corneal neovascularisation. Examples of diseases which include some component of retinal/choroidal neovascularisation include, but are not limited to, Best's diseases, myopia, optic pits, Stargart's diseases, Paget's disease, vein occlusion, artery occlusion, sickle cell anaemia, sarcoid, syphilis, pseudoxanthoma elasticum carotid apo structive diseases, chronic uveitis/vitritis, mycobacterial infections, Lyme's disease, systemic lupus erythematosus, retinopathy of prematurity, Eale's disease, diabetic retinopathy, macular degeneration, Bechet's diseases, infections causing a retinitis or chroiditis, presumed ocular histoplasmosis, pars planitis, chronic retinal detachment, hyperviscosity syndromes, toxoplasmosis, trauma and post-laser complications, diseases associated with rubesis (neovascularisation of the angle) and diseases caused by the abnormal proliferation of fibrovascular or fibrous tissue including all forms of proliferative vitreoretinopathy. Examples of corneal neovascularisation include, but are not limited to, epidemic keratoconjunctivitis, Vitamin A deficiency, contact lens overwear, atopic keratitis, superior limbic keratitis, pterygium keratitis sicca, sjogrens, acne rosacea, phylectenulosis, diabetic retinopathy, retinopathy of prematurity, corneal graft rejection, Mooren ulcer, Terrien's marginal degeneration, marginal keratolysis, polyarteritis, Wegener sarcoidosis, Scleritis, periphigoid radial keratotomy, neovascular glaucoma and retrolental fibroplasia, syphilis, Mycobacteria infections, lipid degeneration, chemical burns, bacterial ulcers, fungal ulcers, Herpes simplex infections, Herpes zoster infections, protozoan infections and Kaposi sarcoma.

Chronic inflammatory diseases associated with uncontrolled angiogenesis may also be treated using PI3K inhibitors of the present invention. Chronic inflammation depends on continuous formation of capillary sprouts to maintain an influx of inflammatory cells. The influx and presence of the inflammatory cells produce granulomas and thus maintains the chronic inflammatory state. Inhibition of angiogenesis using a PI3K inhibitor alone or in conjunction with other anti-inflammatory agents may prevent the formation of the granulosmas and thus alleviate the disease. Examples of chronic inflammatory diseases include, but are not limited to, inflammatory bowel diseases such as Crohn's disease and ulcerative colitis, psoriasis, sarcoidosis, and rheumatoid arthritis.

Inflammatory bowel diseases such as Crohn's disease and ulcerative colitis are characterised by chronic inflammation and angiogenesis at various sites in the gastrointestinal tract. For example, Crohn's disease occurs as a chronic transmural inflammatory disease that most commonly affects the distal ileum and colon but may also occur in any part of the gastrointestinal tract from the mouth to the anus and perianal area. Patients with Crohn's disease generally have chronic diarrhoea associated with abdominal pain, fever, anorexia, weight loss and abdominal swelling. Ulcerative colitis is also a chronic, nonspecific, inflammatory and ulcerative disease arising in the colonic mucosa and is characterised by the presence of bloody diarrhoea. These inflammatory bowel diseases are generally caused by chronic granulomatous inflammation throughout the gastrointestinal tract, involving new capillary sprouts surrounded by a cylinder of inflammatory cells. Inhibition of angiogenesis by these inhibitors should inhibit the formation of the sprouts and prevent the formation of granulomas. Inflammatory bowel diseases also exhibit extra intestinal manifestations, such as skin lesions. Such lesions are characterized by inflammation and angiogenesis and can occur at many sites other than the gastrointestinal tract. Inhibition of angiogenesis by PI3K inhibitors according to the present invention can reduce the influx of inflammatory cells and prevent lesion formation.

Sarcoidosis, another chronic inflammatory disease, is characterized as a multisystem granulomatous disorder. The granulomas of this disease can form anywhere in the body. Thus, the symptoms depend on the site of the granulomas and whether the disease is active. The granulomas are created by the angiogenic capillary sprouts providing a constant supply of inflammatory cells. By using PI3K inhibitors according to the present invention to inhibit angiogenesis, such granulomas formation can be inhibited. Psoriasis, also a chronic and recurrent inflammatory disease, is characterised by papules and plaques of various sizes. Treatment using these inhibitors alone or in conjunction with other anti-inflammatory agents should prevent the formation of new blood vessels necessary to maintain the characteristic lesions and provide the patient relief from the symptoms.

Rheumatoid arthritis (RA) is also a chronic inflammatory disease characterised by non-specific inflammation of the peripheral joints. It is believed that the blood vessels in the synovial lining of the joints undergo angiogenesis. In addition to forming new vascular networks, the endothelial cells release factors and reactive oxygen species that lead to pannus growth and cartilage destruction. The factors involved in angiogenesis may actively contribute to, and help maintain, the chronically inflamed state of rheumatoid arthritis. Treatment using PI3K inhibitors according to the present invention alone or in conjunction with other anti-RA agents may prevent the formation of new blood vessels necessary to maintain the chronic inflammation.

Preferably, the condition is cancer, notably leukaemias including chronic myelogenous leukaemia and acute myeloid leukaemia, lymphomas, solid tumours, and PTEN-negative tumours including PTEN-negative haematological, breast, lung, endometrial, skin, brain and prostrate cancers (where PTEN refers to “phosphatise and tensin homolog deleted on chromosome 10”). More preferably, the condition to be treated by a compound of the invention is rheumatoid arthritis, asthma, chronic obstructive pulmonary disease (COPD), multiple sclerosis, psoriasis and other inflammatory skin disorders, systemic lupus erythematosus, inflammatory bowel disease, and organ transplant rejection. More preferably,

The invention will now be illustrated by the following Examples.

EXAMPLES A. 2-(1H-Indol-4-yl)-6-morpholin-4-yl-pyridin-4-ylamine, 2

i) Synthesis of 2-chloro-6-morpholin-4-yl-pyridin-4-ylamine, 1

A sealed tube charged with 2,6-dichloro-pyridin-4-ylamine (500 mg, 3.1 mmol, 1 eq) and morpholine (2.3 mL, 26.3 mmol, 9 eq) was heated up to 150° C. for 4 h. Once cooled down, the reaction mixture was partitioned with H₂O (10 mL) and extracted with EtOAc (3×20 mL). The combined organic extracts were washed with H₂O (2×5 mL), dried over MgSO₄, and the solvent was removed in vacuo. The resulting residue was further purified by silica gel column chromatography with hexane/EtOAc (1:1-2:3) to furnish 1 as a pink solid (555 mg, 85%).

¹H NMR (400 MHz, DMSO-d₅) δ_(H) ppm: 6.03 (s, 2H), 5.95 (d, J=1.4 Hz, 1H), 5.75 (d, J=1.4 Hz, 1H), 3.62-3.67 (m, 4H), 3.23-3.28 (m, 4H); MS (ES⁺) 214.1 (100%, [M+H]⁺).

ii) Synthesis of 2-(1H-indol-4-yl)-6-morpholin-4-yl-pyridin-4-ylamine, A

To a flask charged with indole-4-boronic acid (791 mg, 4.91 mmol, 3 eq), dichloro-bis(triphenylphosphine)palladium (II) (230 mg, 0.33 mmol, 0.2 eq) and sodium carbonate (348 mg, 3.28 mmol, 2 eq), was added compound 1 (350 mg, 1.64 mmol, 1 eq) dissolved in dioxane/water (40 mL, 3:1). The resulting reaction mixture was then heated at 88° C. for 18 h under Ar(g); once cooled down, it was then partitioned with H₂O (20 mL) and extracted with EtOAc (4×20 mL) and CH₂Cl₂ (15 mL). The combined organic extracts were dried over MgSO₄ and the solvent was then removed in vacuo. The residue was further purified by silica gel column chromatography, eluting with hexane/EtOAc (1:1-0:1), to yield the product as a white solid (273 mg, 56%).

¹H NMR (400 MHz, DMSO-d₅) δ_(H) ppm: 11.12 (br. s, 1H), 7.39 (s, 1H), 7.35-7.38 (m, 2H), 7.12 (s, 1H), 6.87 (br. s., 1H), 6.56 (s, 1H), 5.85-5.88 (m, 1H), 5.74 (br. s., 2H), 3.68-3.74 (m, 4H), 3.37-3.42 (m, 4H); MS (ES⁺) 295.0 (100%, [M+H]⁺).

B. 4-Dimethylamino-N-[2-(1H-indol-4-yl)-6-morpholin-4-yl-pyridin-4-yl]-butyramide

To a solution of 4-dimethylamino-butyric acid hydrochloride, 2 (29 mg, 0.17 mmol, 2 eq) and DIC (26 μL, 0.17 mmol, 2 eq) in DMF (1 mL) was added Et₃N (48 mL, 0.34 mmol, 4 eq) at rt. After 30 min, amine 1 (25 mg, 0.085 mmol, 1 eq) was dissolved in DMF (1 mL) and was added to the reaction mixture, which was then heated at 60° C. for 4 h. Once cooled down, the reaction mixture was partitioned with NaHCO₃ (10 mL) and extracted with EtOAc (3×10 mL). The combined organic extracts were dried over MgSO₄ and the solvent was removed in vacuo.

The resulting residue was further purified by silica gel column chromatography with CH₂Cl₂/MeOH (1:0-9:1+0.3M NH₃) to furnish the product as a white solid (26 mg, 74%).

¹H NMR (400 MHz, CDCl₃) δ_(H) ppm: 10.44 (br. s, 1H), 8.28 (br. s, 1H), 7.54 (d, J=7.4 Hz, 1H), 7.43 (d, J=8.1 Hz, 1H), 7.37 (s, 1H), 7.24-7.30 (m, 2H), 7.07-7.10 (m, 1H), 7.00 (d, J=0.9 Hz, 1H), 3.83-3.88 (m, 4H), 3.63-3.68 (m, 4H), 2.53-2.59 (m, 2H), 2.51 (t, J=5.9 Hz, 2H), 2.36 (s, 6H), 1.90 (quin, J=6.1 Hz, 2H); MS (ES⁺) 408.0 (100%, [M+H]⁺).

C. N-[2-(1H-Indol-4-yl)-6-morpholin-4-yl-pyridin-4-yl]-4-pyrrolidin-1-yl-butyramide

To a solution of 4-pyrrolidin-1-yl-butyric acid hydrochloride, 3, (33 mg, 0.17 mmol, 2 eq) and DIC (26 μL, 0.17 mmol, 2 eq) in DMF (1 mL) was added Et₃N (47 mL, 0.34 mmol, 4 eq) at rt. After 30 min, the amine 1 (25 mg, 0.085 mmol, 1 eq) was dissolved in DMF (1 mL) and was added to the reaction mixture, which was then heated at 60° C. for 4 h. Once cooled, the reaction mixture was partitioned with NaHCO₃ (10 mL) and extracted with EtOAc (3×10 mL) and CH₂Cl₂ (10 mL). The combined organic extracts were dried over MgSO₄ and the solvent was removed in vacuo. The resulting residue was further purified by silica gel column chromatography, eluting with CH₂Cl₂:MeOH (1:0-6:1+0.3M NH₃) to furnish the product as a white solid (4.5 mg, 12%).

¹H NMR (400 MHz, CDCl₃) δ_(H) ppm: 7.48 (d, J=7.3 Hz, 1H), 7.41 (d, J=8.1 Hz, 1H), 7.32 (s, 1H), 7.25 (m, J=3.0 Hz, 1H), 7.18 (t, J=7.7Hz, 1H), 7.12 (s, 1H), 6.95-6.98 (m, 1H), 3.79-3.85 (m, 4H), 3.58 (t, J=4.6 Hz, 4H), 3.26-3.36 (m, 2H), 3.08-3.13 (m, 1H), 3.01 (t, J=7.5 Hz, 2H), 2.54 (t, J=7.0 Hz, 2H), 2.46 (t, J=6.7 Hz, 1H), 1.93-2.08 (m, 4H), 1.16 (t, J=7.1 Hz, 1H), 1.08 (t, J=7.2Hz, 1H), MS (ES⁺) 434.0 (100%, [M+H]⁺).

The following biochemical data have been generated for the exemplified compounds, showing PI3K binding potency.

Biochemical Data IC₅₀ (nM), IC₅₀ (nM), IC₅₀ (nM), IC₅₀ (nM), Compound PI3K-p110α PI3K-p110β PI3K-p110δ PI3K-p110γ B ≧10,000 247 177 ≧10,000 C 953 

1. A compound of formula I:

or a pharmaceutically acceptable salt thereof, wherein: R₁ , R₂, R₃, R₅ and R₆ are each independently (LQ)_(m)Y; each L is independently a direct bond, C₁-C₁₀ alkylene, C₂-C₁₀ alkenylene, C₂-C₁₀ alkynylene, arylene or C₃-C₁₀ cycloalkylene; each Q is independently a direct bond, heteroarylene, a heterocycle linker, —O—, —NR₇— —C(O)—, —C(O)NR₇—, —SO₂—, —SO₂—NR₇—, —NR₇—C(O)—NR₇—, —N—SO₂—NR₇—, —C(halogen)_(a)(R_(7(2-a)))—, —NR₈R₉—, —C(O)NR₈R₉—, where R₈ and R₉ together with the nitrogen to which they are attached form a 5 to 7-membered heterocycle linker; each R₇ is independently H or C₁-C₆ alkyl; m is from 0 to 5; Y is H, C₁-C₁₀ alkyl, C₂-C₁₀ alkenyl, C₂-C₁₀ alkynyl, aryl, C₃-C₁₀ cycloalkyl, heterocycle, heteroaryl, —OR₇, —N(R₇)₂, —C(O)R₇, —C(O)OR₇, —C(O)N(R₇)₂, —N(R₇)₂, —SO₂— R₇, —SO_(2—N(R) ₇)₂, —N—C(O)—N(R₇)₂, —N—SO_(2—N(R) ₇)₂, halogen, —C(halogen)_(b)R_(7(3-b)), —CN, —NR₈R₉—, —C(O)NR₈R₉, where R₈ and R₉ together with the nitrogen to which they are attached form a 5- to 7-membered heterocycle; b is from 1 to 3; a is 1 or 2; R₄ is H, halogen, optionally substituted aryl or optionally substituted alkyl; and; each X is independently CR₇ or N, wherein each aryl, heteroaryl or heterocycle is optionally substituted with up to three substituents selected from C₁-C₆ alkyl, hydroxy, C₁-C₃ hydroxyalkyl, C₁-C₃ alkoxy, C₁-C₃ haloalkoxy, amino, C₁-C₃ mono alkylamino, C₁-C₃ bis alkylamino, C₁-C₃ acylamino, C₁-C₃ aminoalkyl, mono (C₁-C₃ alkyl) amino C₁-C₃ alkyl, bis (C₁-C₃ alkyl) amino C₁-C₃ alkyl, C₁-C₃-acylamino, C₁-C₃ alkyl sulfonylamino, halo, nitro, cyano, trifluoromethyl, carboxy, C₁-C₃ alkoxycarbonyl, aminocarbonyl, mono C₁-C₃ alkyl aminocarbonyl, bis C₁-C₃ alkyl aminocarbonyl, —SO₃H, C₁-C₃ alkylsulfonyl, aminosulfonyl, mono C₁-C₃ alkyl aminosulfonyl and bis C₁-C₃-alkyl aminosulfonyl.
 2. The compound according to claim 1, wherein R₁ is optionally substituted heteroaryl or heterocycle, wherein the optional substituents are as defined in claim
 1. 3. The compound according to claim 1, wherein R₁ is morpholino.
 4. The compound according to claim 1, wherein R₂ is H.
 5. The compound according to claim 1, wherein R₄ is H.
 6. The compound according to claim 1, wherein each X is CH.
 7. The compound according to claim 1, wherein R₅ and/or R₆ is H.
 8. The compound according to any preceding claim wherein R₃ is NR₇R₇.
 9. The compound according to claim, wherein R₃ is NR₇C(O)(C₁-C₁₀ alkylene)NR₈R₉.
 10. The compound according to claim 1, wherein R₃ is NR₇C(O)(C₁-C₁₀ alkylene)NR₇R₇.
 11. The compound according to claim 1, which is selected from: 2-(1H-indol-4-yl)-6-morpholin-4-yl-pyridin-4-ylamine; 4-dimethylamino-N-[2-(1H-indol-4-yl)-6-morpholin-4-yl-pyridin-4-yl]-butyramide; and N-[2-(1H-indol-4-yl)-6-morpholin-4-yl-pyridin-4-yl]-4-pyrrolidin-1-yl-butyramide.
 12. A pharmaceutical composition comprising a compound according to claim 1, and a pharmaceutically acceptable excipient.
 13. A therapeutic method that comprises administering a compound of claim 1 to a subject in need of therapy.
 14. The method according to claim 13, wherein the therapy is of cancer, an immune disorder or an inflammatory disorder.
 15. The method according to claim 14, wherein the cancer is a leukaemia or a PTEN-negative solid tumour.
 16. The method according to claim 13, wherein the therapy is of rheumatoid arthritis.
 17. The method according to claim 13, for use in anti-rejection therapy following an organ transplant. 